Fix unreliable renet2 channels used with websockets

[UkoeHB]

Fixes #43

[UkoeHB]

@alexthill can you test if this PR fixes your issue?

[alexthill]

I tested the change and both the example echo server and my own application now work as expected with WebSockets. Thank you.

One nitpick: These comments should probably be doc-comments?

renet2/renet2/src/channel/mod.rs

Lines 12 to 17 in f48d428

	// Messages can be lost or received out of order.
	Unreliable {
	// Should only be `true` if the underlying transport is ordered and reliable (e.g. WebSockets or in-memory channels)
	// and reliability is desired. Can be set to `false` if reliability is not required.`
	ordered_reliable_substrate: bool,
	},